Production of asbestos yarns

ABSTRACT

In the production of drafted lightweight, high strength asbestos yarn with good strength, uniformity and weaving properties, the occurrence of breaks during drafting and the resultant waste of materials, labor and time are minimized by incorporating an undrawn continuous filament yarn, made of a drawable synthetic polymeric fiber, in each narrow strand or sliver of blended asbestos and staple textile fibers formed from the web thereof emanating from the card and just prior to the entry of the strands into the rub apron system where each strand is compacted and formed into a roving. The filament yarn thus constitutes a base for the asbestos and textile fibers and, by virtue of its drawability, can stretch with the roving during the subsequent drafting thereof and hold the fibers together. The draw ratio of the filament yarn should be approximately the same as, and preferably is slightly greater than, the draft ratio of the asbestos fiber roving. This abstract is not to be taken as either a complete exposition or as a limitation of the present invention, however, the full nature and extent of the invention being discernible only by reference to and from the entire disclosure.

United States Patent [191 Clarkson [111 3,811,262 May 21, 1974 PRODUCTION OF ASBESTOS YARNS [75] Inventor: Robert J. Clarkson, Winnsboro,

[52] US. Cl. 57/140 BY, 57/36, 57/50, 57/144, 57/157 R, 57/160 [51] Int. Cl D02g 3/04, D02g 3/20 [58] Field of Search 57/34 R, 50, 36, 140 R, 57/140 BY, 144, 160, 156, 157 R [56] g References Cited UNlTEDSTATES PATENTS 1,437,438 12/1922 Nanfeldt 57/160 1,439,166 12/1922 Heany 57/160 1,458,577 6/1923 Heany 57/160 1,564,238 12/1925 Heany 57/160 2,748,558 6/1956 Mullenschlader 57/50 X Primary Examiner-John Petrakes Attorney, Agent, or Firm-Norbert P. Holler [5 7] ABSTRACT In the production of drafted lightweight, high strength asbestos yam with good strength, uniformity and weaving properties, the occurrence of breaks during drafting and the resultant waste of materials, labor and time are minimized by incorporating an undrawn continuous filament yarn, made of a drawable synthetic polymeric fiber, in each narrow strand or sliver of blended asbestos and staple textile fibers formed from the web thereof emanating from the card and just prior to the entry of the strands into the rub apron system where each strand is compacted and formed into' a roving. The filament yarn thus constitutes a base for the asbestos and textile fibers and, by virtue of its drawability, can stretch with the roving during the subsequent drafting thereof and hold the fibers together. The draw ratio of the filament yarn should be approximately the same as, and preferably is slightly greater than, the draft ratio of the asbestos fiber roving. This abstract is not to be taken as either a complete exposition or as a limitation of the present invention, however, the full nature and extent of the invention being discernible only by reference to and from the entire disclosure.

23 Claims, No Drawings PRODUCTION OF ASBESTOS YARNS This invention relates to the art of producing drafted asbestos yarn.

ln the-conventional production of drafted asbestos yarn, after the asbestos fiber has been first crushed, opened and cleaned, a mass of such fibers is mixed or blended with a relatively small proportion of staple fibers of a natural or synthetic fibrous textile material, e.g. cotton, polyester and the like. Typically, the blend consists of about 5 parts by weight asbestos and about 1 part textile staple. The resultant blend of fibers is carded to form a relatively wide web or lap which is then divided in any suitable manner into a large number of relatively narrow strands or slivers. Each of the latter is then subjected to a rubbing action in a rub apron system where it is rolled and compacted to form a roving. Finally, each such roving is subjected to a drafting operation, which normally also includes a spinning andtwisting stage, to reduce the thickness of the yarn and to improve its uniformity, strength and appearance.

The drafting of asbestos fiber slivers or rovings formed from the carded lap has presented a major problem in asbestos yarn manufacture, however, particularly in the area of drafting, due to the weakness, short fiber length and lack of cohesion, among other characteristics, of the asbestos fiber. The addition of the aforementioned staple textile fibers to the asbestos fibers prior to carding was, in fact, initially proposed to overcome these drawbacks and to enable the textile staple fibers, which are normally longer than the asbestos fibers, to provide some means for holding the latter together. Other expedients aimed at this end, including the use of adhesive-like impregnants, and the plying of an asbestos fiber roving with one or more fully drawn or undrawable filament yarns have also been proposed. These practices, however, have not been able to minimize the occurrence of breaks in the asbestos yarn both during the various production stages and during the use thereof in fabric manufacture by weaving and the like. Thus, not only has the industry been faced with a considerable waste of both materials and labor, but the manufacture of high qualitydrafted asbestos yarn has been effectively rendered unfeasible as well.

It is an important .object of the present invention; therefore, to provide a novelapproach to asbestos yarn manufacture by means of which the drawbacks thereof heretofore encountered are minimized andthe production of drafted asbestos yarn of high quality and with minimum waste of materials and labor greatly facilitated.

Generally speaking, the objectives of the present invention are attained by incorporating in each carded asbestos fiber sliver, immediately prior to the delivery thereof to the rub apron system, an undrawn continuous filament yarn made of a drawable synthetic polymeric fiber. Representative polymeric fibers of this type are nylon, polyester, and polypropylene. The term undrawn as used herein is intended to designate any continuous filament yarn which either has not been drawn at all or has been drawn only partially or less than fully so as to have a residual drawability or draw ratio less than its initially provided higher than desired or needed draw ratio. The draw ratio of the undrawn filament yarn should be approximately the same as the intended draft ratio of the asbestos fiber roving, and

preferably should be at least about 2 and slightly greater than the draft ratio. In the roving, the filament yarn provides a base to which the blended asbestos and other staple fibers can cling and by which they are held together. Thus, since the filament yarn is stretched simultaneously with and to the same extent as the roving during the drafting operation, the filament yarn serves to minimize the occurrence of breaks in the asbestos yarn during the production thereof. The filament yarn, of course, when ultimately substantially fully drawn (and it will be understood that in this state the filament yarn may still be slightly less than fully drawn) also enhances the strength and uniformity-of the asbestos yarn and renders it highly resistant to the occurrence of breaks and skin-back effects during any weaving or like fabric-forming operation.

In a typical actual production of drafted lightweight asbestos yarn according to the present invention, which is here set forth as an example of the practice of the invention, the carded lap or web of asbestos fibers and textile staple is split in any suitable manner into 66 strands or slivers, of which, to facilitate the processing, one group of 33 ends is fed to a rub apron system located at a level above that of the card web and the second group of 33 ends to another rub apron system at a level below that of the card web. The required 66 undrawn continuous filament yarns, e.g. denier nylon yarns each having the requisite'draw ratio (which may vary indifferent cases but in a representative situation may be about 2.25 for an intended draft ratio of about 2 for the roving), are taken from suitably located creels and fed in two groups of 33 ends each via respective guide tubes, for example low friction flexible metal conduits covered by air-impervious coatings or sleeves of likewise flexible synthetic plastics such as polyethylene and the like, to the regions just ahead of the entry locations of the rub apron systems. There each of the undrawn filament yarns is laid into a respective one of the passing asbestos fiber strands. The filament yarn feed can be initiated by air under a pressure of about 5 psi, but once the leading end sections of the yarns have been blown into their associated slivers, the forward motion of the latter into the rub apron systems is sufficient to continue the yarn feed. In the rub apron systems, the 66 asbestos/staple strand and filament yarn composites are then subjected to the usual rubbing operation and are compacted into respective rovings. If desired, these rovings may then also have a relatively low twist imparted thereto, e.g. in the range of about /2 3 turns per inch, prior to the drafting of the rovings. Y

As will be clear to-those skilled in the art, each of the various filament yarns incorporated in a roving in accordance with the principles of the present invention will constitute a base for the asbestos and textile fibers in that roving and will tend to hold the fibers together. The fundamental achievement of the present invention is that this relationship remains intact even when the roving is subsequently drafted, during which stage the undrawn filament yarn, by virtue of its drawability (but v independently of its starting or final denier values, both of which may vary widely subject only to the conditions mandated by the ultimately to be obtained asbestos yarn characteristics), will stretch with and to the same extent as the asbestos fiber strand while continuing to hold the fibers together. The occurrence of breaks in the asbestos yarn during all stages of the production thereof is, therefore, effectively minimized. In this con,-

nection it should-be mentioned ,thattheroving may also 7 be subjected to a, spinning or twisting operation as an adjunct of the drafting operation, for example either prior to or while being wound up onto a take-up spool, for the purpose of imparting a certain degree of twist to the so-fo'rmed yarn (as is conventionalwith most textile filament or fiber yarns). It is thus contemplated that the term drafting" (as well as any noun, verbal and adjectival variant thereof) as used in this specification and the appended'claim's beinterpreted in its broadest sense to embrace within its scope both draftingas such and drafting associated with or followed by spinning and twisting.

Finished asbestos yarn produced in accordance with the foregoing example of the present invention is found to have an asbestos fiber content of about 80 percent and to be possessed of good feel and uniformity, making it suitable for use in such applications as fireproof high quality furniture and clothing fabrics. Moreover,

'by virtue of the continued presence of the substantially fully drawn filament yarn, the finished asbestos yarn is found to have good strength and resistance to skinbacks, which makes it capable of use in weaving and like fabric-forming operations where yarn stresses tend to be very high. If desired, of course, the asbestos yarn may also be plied with one or more fully drawn or undrawable additional yarns of natural or synthetic textile fibers, e.g. yarns made of cotton, rayon, nylon, polyester, glass fiber, acrylic fiber, etc., for added strength, but the structure of the asbestos yarn according to the present invention makes it possible to omit this step without anyadverse effect on the utility of the yarn.

It will be understood that the foregoing description of the present invention is for purposes of illustration only,.and that the various aspectsand features of the products and processes herein disclosed are susceptible to a number of modifications and changes none of which entails any departure from the spirit and scope of the present invention as defined in the hereto appended claims. r

Having thus described'the invention, what is claimed and desired to be protected by Letters Patent is:

1. In the method of making asbestos yarn; the improvement comprising feeding and laying an undrawn continuous filament yarn of aldrawable synthetic polymeric fiber into anunrubbedstrand of a carded blend of a major proportion of asbestos fibers and a minor proportion of relatively longer staple fibers of a natural or synthetic textile materiaLand subjecting the fiber strand and filament yarn composite to a rubbing operation for compacting said composite to form a roving in which saidxfilamentyarn constitutes a base for said asbestos and textile fibers, whereby said roving may be drafted with the occurrence "of breaks greatly-minimized by virtue of the drawability of said filament yarn.

2. The method of claim 1, wherein the draw ratio of said filamentyarn. is approximately equal to the. intended draft ratioof said roving.

3. The method of claim 2, wherein said draw ratio is at least about 2.

4. The method of claim 1, wherein said filament yarn is slightly greater than the intended draft ratio of said roving. f

5. The method 'of claim 4, wherein said drawratio is at least about 2.

the'draw ratio of I 6. The method of claim 1, wherein said drawable synthetic polymeric fiber is nylon, polyester or polypropylene.

7. in the method of making asbestos yarn; the steps comprising feeding and laying an undrawn continuous filament yarn of a drawable synthetic polymeric fiber into an unrubbed strand of a carded blend of a major proportion of asbestos fibers and a minor proportion of relatively longer staple fibers of a natural or synthetic textile material, subjecting'the fiber strand and filament yarn composite to a rubbing operation for compacting said composite to forin a'roving, anddrafting said roving to form asbestos yarn, said filament yarn by virtue of its drawability constituting a base for said asbestos and textile fibers and serving to minimize the occurrence of breaks in said roving during the drafting thereof.

8. The method of claim 7, wherein the draw ratio of said filament yarn is approximately equal to the draft ratio of said roving.

9. The method of claim 8, wherein said draw ratio is at least about 2. 2

10. The method of claim 7, wherein thedraw ratio of said filament yarn isslightly greater than the draft ratio of said roving. v

11. The method ofclaim l0, wherein said draw ratio is at least about 2. V i 7 12. The method of claim 7, wherein said drawable synthetic polymeric fiber is nylon, polyester or polypropylene. i I v 13. in the method of making asbestos yarn; the steps comprising carding a blend of a major proportion of asbestos fibers and a minor proportion of relatively longer staple fibers of a natural or synthetic textile material to form a web, dividing said web into a plurality of relatively narrower strands, advancing said. strands toward respective rubbing stations, feeding and laying into each of said strands, prior to its entry into a rubbing station, a respective undrawn continuous filament yarn of a drawable synthetic polymeric fiber, thereafter subjecting each fiber strand and filament yarn composite toa rubbing operation for compacting each composite to form a respective roving, and drafting said rovings to form asbestos yarns, said filament yarns by virtue of their drawability constituting'respective bases for the associated asbestos and textile fibers and serving to minimize the occurrence of breaks in the respective rovings during the drafting thereof.

14. The method of claim l3, wherein said drawable synthetic polymeric fiber is nylon, polyester or polypropylene.

I5.'The method of claim 13, further comprising the step of plying at least one additional yarn of natural or synthetic textile fiber material with each of said drafted rovings. v 3

e 16. The method of claim 13, wherein the amount of said asbestos fibers used in said blend is predetermined to ensure that in each of said asbestos yarns said asbestos fibers constitute about percent of the yarn by weight based on the weight'of the yarn.

17. Asbestos yarn made by the process of claim 16.

18. The method of claim 13, wherein the draw ratio of each of said filament yarns is at least about 2.

19. The method of claim 18, wherein said draw ratio is slightly greater than the draft ratio of said rovings.

3,81 1,262 6 20. The method of claim 13 wherein the leading end claim 1. region of each of said undrawn filament yarns is fed into its respective one of saidvstrands by a pressurized air stream.

21. An asbestos fiber roving made by the process of 5 22.. Asbestos yarn made-by the process of claim 7. 23. Asbestos yarn made by the process of claim 13. 

2. The method of claim 1, wherein the draw ratio of said filament yarn is approximately equal to the intended draft ratio of said roving.
 3. The method of claim 2, wherein said draw ratio is at least about
 2. 4. The method of claim 1, wherein the draw ratio of said filament yarn is slightly greater than the intended draft ratio of said roving.
 5. The method of claim 4, wherein said draw ratio is at least about
 2. 6. The method of claim 1, wherein said drawable synthetic polymeric fiber is nylon, polyester or polypropylene.
 7. In the method of making asbestos yarn; the steps comprising feeding and laying an undrawn continuous filament yarn of a drawable synthetic polymeric fiber into an unrubbed strand of a carded blend of a major proportion of asbestos fibers and a minor proportion of relatively longer staple fibers of a natural or synthetic textile material, subjecting the fiber strand and filament yarn composite to a rubbing operation for compacting said composite to form a roving, and drafting said roving to form asbestos yarn, said filament yarn by virtue of its drawability constituting a base for said asbestos and textile fibers and serving to minimize the occurrence of breaks in said roving during the drafting thereof.
 8. The method of claim 7, wherein the draw ratio of said filament yarn is approximately equal to the draft ratio of said roving.
 9. The method of claim 8, wherein said draw ratio is at least about
 2. 10. The method of claim 7, wherein the draw ratio of said filament yarn is slightly greater than the draft ratio of said roving.
 11. The method of claim 10, wherein said draw ratio is at least about
 2. 12. The method of claim 7, wherein said drawable synthetic polymeric fiber is nylon, polyester or polypropylene.
 13. In the method of making asbestos yarn; the steps comprising carding a blend of a major proportion of asbestos fibers and a minor proportion of relatively longer staple fibers of a natural or synthetic textile material to form a web, dividing said web into a plurality of relatively narrower strands, advancing said strands toward respective rubbing stations, feeding and laying into each of said strands, prior to its entry into a rubbing station, a respective undrawn continuous filament yarn of a drawable synthetic polymeric fiber, thereafter subjecting each fiber strand and filament yarn composite to a rubbing operation for compacting each composite to form a respective roving, and drafting said rovings to form asbestos yarns, said filament yarns by virtue of their drawability constituting respective bases for the associated asbestos and textile fibers and serving to minimize the occurrence of breaks in the respective rovings during the drafting thereof.
 14. The method of claim 13, wherein said drawable synthetic polymeric fiber is nylon, polyester or polypropylene.
 15. The method of claim 13, further comprising the step of plying at least one additional yarn of natural or synthetic textile fiber material with each of said drafted rovings.
 16. The method of claim 13, wherein the amount of said asbestos fibers used in said blend is predetermined to ensure that in each of said asbestos yarns said asbestos fibers constitute about 80 percent of the yarn by weight based on the weight of the yarn.
 17. Asbestos yarn made by the process of claim
 16. 18. The method of claim 13, wherein the draw ratio of each of said filament yarns is at least about
 2. 19. The method of claim 18, wherein said draw ratio is slightly greater than the draft ratio of said rovings.
 20. The method of claim 13, wherein the leading end region of each of said undrawn filament yarns is fed into its respective one of said strands by a pressurized air stream.
 21. An asbestos fiber roving made by the process of claim
 1. 22. Asbestos yarn made by the process of claim
 7. 23. Asbestos yarn made by the process of claim
 13. 